The present invention relates to a smelting furnace comprising
a sole made of a refractory material contained in a metallic casing with expansion joints, and PA1 elastic return means to have the casing following the contraction of the sole.
The aim of the expansion joints is to avoid destruction of the metallic casing by phenomenons of swelling, expansion and contraction of the refractory material, while the aim of the elastic return means is to allow the functioning of the expansion joints.
Such a furnace is described in Belgian Pat. No. 411 323. In this known furnace a sheet is inserted where the joints are provided, between the sole and the metallic casing so as to avoid that refractory material of the sole penetrates into the opening of the joints. No measure is taken, however, to avoid that liquid phase, that infiltrates into the refractory sole and reaches a joint, flows through this joint. This known furnace is thus not suited to carry out metallurgical reactions producing a liquid phase, the melting point of which is markedly lower than the reaction temperature, since under these conditions the liquid phase has a strong tendency to infiltrate deeply into the sole. Such a situation occurs, for instance, when lead bearing ores or concentrates are smelted to yield a slag phase and a lead bullion phase: the melting point of the slag requires an operating temperature of some 1,200.degree. C., while the melting point of the lead bullion is about 330.degree. C.